Communications systems presently depend upon either earth based systems of wires, cables, microwave towers, wireless networks or earth-orbiting satellites. Each of these two delivery systems suffers from a variety of limitations. In the case of ground (or sea) based communications systems, the cables must be laid, or microwave towers or wireless base stations erected, incurring heavy financial and even political costs. The services provided by ground-based systems may prove to be economically attractive only where the population density of potential subscribers is substantial. Moreover, the elements of such terrestrially based, hard-wired systems require periodic maintenance and upgrading, also at great expense.
Satellite-based communications networks suffer from their own shortcomings. Most conspicuously, they cannot be placed into service without being boosted by rockets. Rocket technology is an extraordinarily expensive means for placing a platform into service. The fact that rockets have a high failure rate increases both the risk of loss and the cost of launch due to insurance. The use of rockets also incurs serious environmental costs, since most commercially used rockets produce thousands of tons of toxic emissions each time they are launched.
Furthermore, the nature of satellite orbits imposes certain constraints on their utility. Satellites placed in geostationary orbit (of which there is only one, located approximately 22,291 miles above the earth's equator) are limited in terms of the number of available positions or "slots." The great distance of geostationary satellites from the earth leads to significant attenuation of signals transmitted to and received from these platforms. To cope with this attenuation, either expensive ground-based equipment or larger, more powerful satellites must be used. The distance of geostationary satellites from the earth also introduces non-trivial delays in the delivery of signals.
Satellites placed in low-earth orbit, while more attractive than geostationary satellites from the standpoint of deployment costs, signal attenuation and delay, nevertheless suffer from their own infirmities. Perhaps the chief among these is that the speeds at which the satellites traverse regions of the earth confine the duration of suitable transmission periods to mere minutes. The provision of meaningful communications coverage accordingly requires the use of many such satellites in conjunction with a complex yet robust system for controlling communications among them.
Certain systems that would employ one or more lighter than air platforms deployed in the atmosphere have been proposed as an alternative to the existing ground-based and space-based communications network options. These proposed systems employ an approach in which each platform is intended to maintain a fixed position or station above the earth in the face of environmental disturbances. This approach consumes a great deal of energy, however, and requires that the platform be outfitted, at great expense and increase in weight, with an on-board source of, or means of capturing, the necessary energy.